2170721 has 8 divisors (see below), whose sum is σ = 2528064. Its totient is φ = 1825200.

The previous prime is 2170703. The next prime is 2170723. The reversal of 2170721 is 1270712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2170721 - 2⁶ = 2170657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2170693 and 2170702.

It is not an unprimeable number, because it can be changed into a prime (2170723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2555 + ... + 3296.

It is an arithmetic number, because the mean of its divisors is an integer number (316008).

2^2170721 is an apocalyptic number.

It is an amenable number.

2170721 is a deficient number, since it is larger than the sum of its proper divisors (357343).

2170721 is an equidigital number, since it uses as much as digits as its factorization.

2170721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5911.

The product of its (nonzero) digits is 196, while the sum is 20.

The square root of 2170721 is about 1473.3366892873. The cubic root of 2170721 is about 129.4795960758.

Subtracting from 2170721 its reverse (1270712), we obtain a palindrome (900009).

The spelling of 2170721 in words is "two million, one hundred seventy thousand, seven hundred twenty-one".